The present invention relates to devices used to control the flow of fluid through vehicle fluid systems, such as a vehicle anti-lock brake system.
For safety concerns, many of today""s vehicles are equipped with anti-lock brake systems (ABS). An ABS maintains vehicle control during extreme braking by electronically sensing when the wheels are just about to lock up and releasing the brakes before lock up occurs. An ABS is capable of modulating the pressure in the wheel cylinders in order to keep the wheels from slipping on the roadway during harsh braking conditions. An extension of the ABS is traction control, whereby sufficient traction is maintained between the driving surface and the vehicle by selectively applying ABS without driver input.
In general, a typical anti-lock brake system can include several solenoid valves to control the hydraulic fluid pressure in the individual components, e.g., a master cylinder, a plurality of wheel cylinders, and a system pump. One such solenoid valve is the traction control solenoid valve. The traction control solenoid valve is normally open to establish fluid communication between the master cylinder and wheel and to block fluid communication between the master cylinder and a hydraulic system pump. On the other hand, the traction control solenoid valve can close under traction control conditions to block fluid communication between the master cylinder and the wheel. When closed, the traction control solenoid valve establishes fluid communication between the master cylinder and a system pump which, in turn, provides fluid pressure to the wheel cylinder to control application of the brakes. If the fluid pressure within the brake line connecting the pump to the wheel cylinder increases beyond a safe limit, the traction control solenoid valve must also serve as a high pressure relief valve in order to provide proper traction control and to prevent damage to the ABS and brake lines.
It is desirable that a traction control solenoid valve be able to serve both functions: blocking fluid communication between the master cylinder and wheel cylinder under traction control conditions, while priming the system pump, and relieving high pressure in the wheel cylinder. However, the present invention further understands that conventional traction control solenoid valves include numerous internal parts in order to provide the necessary fluid flow control which, in turn, increases production time and costs. Moreover, the present invention recognizes that conventional traction control solenoid valves provide high pressure relief by utilizing an internal spring pre-load that can be overcome by high fluid pressure to open the valve. Unfortunately, the present invention recognizes that these spring-based valves provide inconsistent high pressure relief due to variations in the tolerances of the many internal components.
The present invention has recognized these prior art drawbacks, and has provided the below-disclosed solutions to one or more of the prior art deficiencies.
A vehicle solenoid valve for a vehicle fluid system includes a plunger housing that establishes a first fluid communication path and a second fluid communication path. A plunger is slidably disposed relative to the plunger housing, and the plunger is movable between a de-energized configuration, wherein fluid communication through the first fluid communication path is permitted and fluid communication through the second fluid communication path is blocked, an energized configuration, wherein fluid communication through the first fluid communication path is blocked and fluid communication through the second fluid communication path is permitted, and a pressure relief configuration, wherein, while the valve is energized, fluid pressure on the plunger surpasses a predetermined pressure level to overcome an opposing magnetic force on the plunger and permit fluid communication through the first fluid communication path.
In a preferred embodiment, the plunger defines a proximal end and the valve further includes an armature that forms a central bore. Preferably, the proximal end of the plunger is disposed within the central bore of the armature. Moreover, a coil surrounds the armature and is magnetically coupled thereto. The coil is selectively energizable to urge the armature and, hence, the plunger from the de-energized configuration to the energized configuration. A coil case surrounds the coil and the armature and at least partially surrounds the plunger housing. Also, an armature cup, that has a closed proximal end and an open distal end, surrounds the armature. Preferably, the plunger housing is at least partially disposed within the open distal end of the armature cup.
As intended by the presently preferred embodiment, the plunger housing forms a bore having a first portion and a second portion, and the plunger housing establishes a system pump valve seat between the first portion and second portion of the bore. Furthermore, the plunger defines a distal end, and the plunger is at least partially disposed within the first portion of the bore in the plunger housing. Preferably, the valve includes an integral pin that extends from the distal end of the plunger. The outer diameter of the pin is smaller than the inner diameter of the first portion of the bore, and an annular fluid passage is established between the pin and the plunger housing within the first portion of the bore.
In a preferred embodiment, a valve fitting is disposed within the second portion of the plunger housing bore. The valve fitting defines a first portion and a second portion, with a spring contact face being established therebetween. The valve fitting also forms a wheel cylinder fluid passage circumscribed by a wheel cylinder valve seat. Preferably, the plunger housing forms at least one master cylinder port and at least one system pump port. The first fluid communication path is established by the master cylinder port and the wheel cylinder fluid passage when the valve is in the de-energized configuration. On the other hand, the second fluid communication path is established by the master cylinder port, the annular fluid passage, and the system pump port when the valve is in the energized configuration.
In a preferred embodiment, the valve also includes a plunger ball that contacts the distal end of the pin. The plunger ball engages the system pump valve seat to block fluid communication between the master cylinder port and the annular fluid passage when the valve is deenergized. Also, the ball engages the wheel cylinder valve seat to block fluid communication between the master cylinder port and the wheel cylinder fluid passage when the valve is energized.
In another aspect of the present invention, a valve for a vehicle includes a coil case. An armature cup that has an open end and a closed end is disposed within the coil case, and a plunger housing extends from the open end of the armature cup. The plunger housing establishes a first fluid communication path and a second fluid communication path. In this aspect of the present invention, an armature that forms a bore is reciprocably disposed within the armature cup between the plunger housing and the closed end of the armature cup. A plunger is slidably disposed within the plunger housing. The plunger defines a proximal end which is disposed within the bore formed by the armature. Moreover, the plunger is movable between a de-energized configuration, wherein fluid communication through the first fluid communication path is permitted and fluid communication through the second fluid communication path is blocked, an energized configuration, wherein fluid communication through the first fluid communication path is blocked and fluid communication through the second fluid communication path is permitted, and a pressure relief configuration, wherein, while the valve is energized, fluid pressure on the plunger surpasses a predetermined pressure level to overcome an opposing magnetic force on the plunger and permit fluid communication through the first fluid communication path. Also, in this aspect of the present invention, a coil closely surrounds the armature cup and is magnetically coupled to the armature. The coil is selectively energizable to urge the armature and, hence, the plunger from the de-energized configuration to the energized configuration.
In yet another aspect of the present invention, a system for stabilizing a vehicle includes a master cylinder, at least one wheel cylinder, a system pump, and a vehicle solenoid valve. The vehicle solenoid valve is in fluid communication with the master cylinder, the wheel cylinder, and the system pump. Moreover, the vehicle solenoid valve selectively directs hydraulic brake fluid between the master cylinder and the wheel cylinder and between the master cylinder and the system pump. As intended by this aspect of the present invention, when fluid pressure surpasses a predetermined pressure level, an opposing magnetic force generated by an energized coil is overcome to relieve the pressure.
The present invention will now be described, by way of example, with reference to the accompanying drawings, in which: